1. Field of the Invention
The present invention generally relates to an apparatus for cooling a person or group of people in a microenvironment. The microenvironment can comprise a housing for a controlled physical environment in which the person or the group of people can survive under surrounding inhospitable conditions.
One embodiment of the present apparatus provides a conditioned airflow inside a protective suit, such as a fireman's turn-out gear or a Hazardous-Materials (Haz-Mat) suit, by diverting a portion of the breathing respirator gas stream to an ejector. The breathing respirator, such as a liquefied-gas type respirator, includes an endothermic heat exchanger for cooling and/or dehumidification of the air in the protective suit microenvironment. The air in the microenvironment is cooled and dehumidified by circulating the air over and contacting it with a heat exchanger. The circulation is set up by the ejector which expands a diverted portion of the breathing gas across a nozzle and into a venturi to create a low pressure zone for entraining the microenvironment air inside the protective suit. The conditioned air is directed to the user's body and particularly the head and upper torso, resulting in reduced user heat stress.
2. Prior Art
Ejector devices including a venturi used to cool a person wearing a protective suit are known in conventional practice. Examples of prior art ejector devices are found in U.S. Pat. Nos. 2,984,994 to Hankins; 3,064,448 to Whittington; 3,117,426 to Fischer et al. and 3,227,208 to Potter, Jr. et al. However, these ejector devices do not segregate the conditioned microenvironment air within the suit, from the breathing gas flowing to the user. Instead, the prior art ejector devices mix these air streams. Mixing the conditioned microenvironment air with the breathing gas supply is unacceptable in those situations when the user is working in a hostile environment where the ambient air outside the microenvironment can adversely influence the air inside. This can occur, for example, when the user is a firefighter working around a burning structure or a pilot flying a high altitude aircraft.
Also, if the breathable gas mixture produced by the respirator device is oxygen rich, the potential for combustion hazards are eliminated for all intents and purposes since the cooling apparatus of the present invention does not employ electrical means which are known ignition sources. In any prior art air conditioning system using an electrical power supply to drive a motor/blower apparatus, sparking is a possibility. Typically, a brushless type motor is needed in these prior art devices to help reduce the possibility for sparking hazard. Electrical shorts, however, are still viable ignition sources and are not mitigated.